Apparatus for delivering waste fluids for combustion

ABSTRACT

An apparatus and method for passing waste fluids into a flare stack for combustion, passing air substantially continuously into said stack while passing waste fluids thereinto, and controllably passing additional air into the flare stack in response to the flow rate of waste fluids into said stack.

United States Patent [191 [111 3,837,785

Evans et al. 1 Sept. 24, 1974 APPARATUS FOR DELIVERING WASTE [56]References Cited Inventors: Robert Evans; David 2,779,399 1/1957 Zink etal. 431/202 Simmons, Jr., both of Sweeny, Tex. 3,771,940 11/1973Stranahan et al 431/5 X [73] Assignee: Phillips Petroleum Company,

Bartlesville, Okla, Primary Examiner-Edward G. Favors 22 Filed: May 29,1973 21 A l N 364 919 [57] ABSTRACT I 1 pp o" An apparatus and methodfor passing waste fluids into a flare stack for combustion, passing airsubstantially Cl u 23/277 continuously into said stack while passingwaste fluids 431/90, 43 thereinto, and controllably passing additionalair into [51] Int. Cl. F23d 13/20 the flare sta k in response to theflow rate of waste [58] Field of Search 431/5, 12, 90, 202; fl id i t idta k,

8 Claims, 1 Drawing Figure P] AIR AIR 4 WASTE FLUID I4 PATENIEDSEP241974AIR WASTE FLUID APPARATUS FOR DELIVERING WASTE FLUIDS FOR COMBUSTION Itis desirable to provide apparatus and method for decreasing the smokeemitted during the combustion of waste fluids. A sample use would be inthe combustion of waste oil vapor and other waste hydrocarbons from ahydrocarbon processing plant.

In heretofore utilized similar apparatus, a single blower will injectair into the stack to support combustion of the fuel. However, at lowrates of injection of the waste fluid, the blower will not be actuatedowing to the fluid flow rate sensing apparatus not being sufficientlysensitive at the low rates of fluid flow. This is particularly truewhere the waste fluid flow varies between, for example, 100 scfm to2,000 scfm. In such situations, the piping necessary to handle 2,000scfm will be so large that when the low values are passing the controlequipment will not be actuated.

This invention, therefore, resides in an apparatus and method forpassing waste fluids into a flare stack for combustion, passing airsubstantially continuously into said stack while passing waste fluidsthereinto, and con trollably passing additional air into the flare stackin response to the flow rate of waste fluids into said stack.

Other aspects, objects, and advantages of the present invention willbecome apparent from a study of the disclosure, the appended claims, andthe drawing.

The drawing is a diagrammatic view of the apparatus of this invention.Referring to the drawing, a flare stack 2 is connected in fluidcommunication with a waste fluid conduit 4. A first air injecting means6, for example a fan, compressor, or other apparatus known in the art,is connected in fluid communication with the flare stack 2.

The first air injecting means 6 has a first power source 8, for examplean electric motor, connected thereto for operating said air injectingmeans 6. A control means 10 is connected to the first power source 8 andto measuring-signaling means 12 associated with the waste fluid conduit4. The control means 10 can be a mercoid switch or pressure switch, forexample, and the measuring-signaling means can be a Pitot tube, orificemeter, or other flow measuring means having a signal transmitted fordelivering a signal responsive to the measure of flow.

A second air injecting means 14 having a second power source 16 isconnected in fluid communication with the flare stack 2 forsubstantially continuously passing an air stream into the stack whilewaste fluid is passing into said stack. It is preferred that thedischarge of the second air injecting means 14 be connected to thesuction of the first air injecting means 6..

In the method of this invention, a first stream of air from the thirdmeans is substantially continuously passed into the flare stack 2 whilepassing waste fluids into the stack and into contact with the air streamfor mixing therewith. The mixture passes upwardly through the stack andis combusted. A pilot light (not shown) is associated with the stack forignition of the waste fluid-air mixture. As the flow of waste fluid intothe stack 2 increases, the rate of flow through conduit 4 will becomesufficient to be detected by the measuring-signaling means 12 which willin turn deliver a sig- 6 nal via hne 18 for actuating power source 8 andfirst air injecting means 6 via control means 10. An example operationis as follows:

In the operation of a flare at a terminal storing ethylene, propylene,natural gas liquids, debutanized natural gas liquids, isobutane, andnormal butane, a maximum release of 1,900 standard cubic feet per minuteof combustible gases was expected. Small continuous releases ofapproximately to 200 scfm occurred. The velocity measuring device whichobtained these measurements through use of a three-position Pitot tubewould not actuate the mercoid switch to initiate operation of the blowerwhich provided 9,280 scfm of combustion air and 4 inches of water headinto the stack. The vapors when burned without excess combustion airproduced smoke. A continuously operating one-half horsepower blowerblowing through the suction of the main blower was installed andprovided adequate air (1,560 scfm of combustion air at inch of waterhead) for smokeless operation in'the range below that at which the largevolume blower did not operate. During operation, the large volume bloweroperated approximately one percent of the time while the small bloweroperated continuously.

Other modifications and alterations of this invention will becomeapparent to those skilled in the art from the foregoing discussion andaccompanying drawing, and it should be understood that this invention isnot to be unduly limited thereto.

What is claimed is:

1. An apparatus for delivering waste fluid for combustion comprising aflare stack,

means for passing waste fluids into said flare stack,

measuring means for measuring the flow rate of said waste fluids passinginto said flare stack and delivering a signal in response to said rate,

first means for passing air substantially continuously into said flarestack while passing waste fluid into said flare stack, and

second means for passing additional air into said flare stack beingarranged in operational relationship with said measuring means so as tobe actuated by said signal.

2. Apparatus in accordance with claim 1 wherein said second meanscomprise a first air injecting means connected to said flare stack so asto inject air into said flare stack when actuated,

a first power means connected to said first air injecting means, and

control means receiving said signal from said measuring means andactuating said first power means.

3. Apparatus in accordance with claim 2 wherein said first meanscomprises a second air injection means connected in fluid communicationto said flare stack, and

a second power source connected to said second air injecting means so asto substantially continuously pass air into said flare stack whilepassing waste fluids into said flare stack. 7

4. Apparatus in accordance with claim 3 wherein a discharge of saidsecond air injecting means is connected to the suction of said first airinjecting means.

5. Apparatus in accordance with claim 2 wherein said control means isarranged in such operational relationship between said measuring meansand said first power means that said control means actuates said firstpower the flare stack, and

passing a second stream of additional air into the flare stack inresponse to said signal.

7. A method, as set forth in claim 6, wherein the first and secondstreams of air passed together into the flare stack.

8. A method, as set forth in claim 6, wherein the first air streampasses into the flare stack in response to the flow rate of the wastefluids being greater than a preselected value.

1. An apparatus for delivering waste fluid for combustion comprising a flare stack, means for passing waste fluids into said flare stack, measuring means for measuring the flow rate of said waste fluids passing into said flare stack and delivering a signal in response to said rate, first means for passing air substantially continuously into said flare stack while passing waste fluid into said flare stack, and second means for passing additional air into said flare stack being arranged in operational relationship with said measuring means so as to be actuated by said signal.
 2. Apparatus in accordance with claim 1 wherein said second means comprise a first air injecting means connected to said flare stack so as to inject air into said flare stack when actuated, a first power means connected to said first air injecting means, and control means receiving said signal from said measuring means and actuating said first power means.
 3. Apparatus in accordance with claim 2 wherein said first means comprises a second air injection means connected in fluid communication to said flare stack, and a second power source connected to said second air injecting means so as to substantially continuously pass air into said flare stack while passing waste fluids into said flare stack.
 4. Apparatus in accordance with claim 3 wherein a discharge of said second air injecting means is connected to the suction of said first air injecting means.
 5. Apparatus in accordance with claim 2 wherein said control means is arranged in such operational relationship between said measuring means and said first power means that said control means actuates said first power means only when said flow rate measured by said measuring means is greater than a preselected value.
 6. A method for delivering waste fluids for combustion, comprising: passing waste fluids into a flare stack; measuring the flow rate of the waste fluids passing into said flare stack, delivering a signal in response to said measured flow rate, passing a first stream of air substantially continuously into the flare stack while passing waste fluid into the flare stack, and passing a second stream of additional air into the flare stack in response to said signal.
 7. A method, as set forth in claim 6, wherein the first and second streams of air passed together into the flare stack.
 8. A method, as set forth in claim 6, wherein the first air stream passes into the flare stack in response to the flow rate of the waste fluids being greater than a preselected value. 